The 'Screw-Ship' For Your OSR Post Apocalyptic Retro Future Campaign

Original Source HERE 

Atomic Powered Screw Ship 

Required Crew: 59 (109  capacity) 

Top Speed: Surfaced (17.55 mph; 28.24 km/h) 

Submerged: (70 mph)

Cargo: 100 men or 20,000lbs (normal complement 20 marines)

Structural Hit Points: 150

Armour: AC:3

Weapons : Laser cannon (6d10 x 2, 3000’ range)

Under Water Capacitor Battery ( 4d6 to everything within a 1,000' range) drains the screw ship for 4 rounds per use. 

10 micro torpedo launchers treat as mini missile launchers with 'fire and forget'  pin point guidance systems. 

Power Source : Niles Nuclear Reactors 

Originally used for cargo transportation by the Ancients before the collapse of society and the known world. These Atomic powered behemoths were used for incredibly rapid transport between the waves and nations. Since then several warlords with close ties to under water communities have resurrected these giants and used them for troop transportation and invasion of several coastal cities in the Mutant Future. 

These incredible artifacts have been warred over by several aquatic factions over the years. There are rumors of under water bases where 'screw ships' have been stored. Still these are mere urban legend or true fish tales. 

 The operation of the screw ship 

"Resembling a torpedo in general appearance, the proposed underwater craft consists of two parts. One, a cylinder-like inner chamber, features the crew’s rooms, the storage hold, engines (electric) and a gyro device to maintain balance. The other part of the future “screw-ship” consists of a steel outer jacket which rotates around the stationary inner chamber by means of a special gear and bearing arrangement and which has spiral-shaped metal fins fastened to its surface. When the engines cause the outer jacket to rotate, the spiral fins screw into the water much as the threads of a screw bite into wood, thus forcing the craft forward. A periscope at the nose and a rudder at the rear facilitate steering." 

Additional properties 

Because of the nature of these ships,these cargo vessels are strangely silent and very hard to detect underwater. It is unknown if this was intentional or part of the design of the 'Screw Ship' by the Ancients. 

Parts, maintenance,dry docking, and other routine upkeep must be done in a well equipped facility. Parts are extremely hard to come by and many underwater mutant communities hoard such items as collateral against attack by local warlords.

Local Rumors  

There have also been reports out of the waters of the ChineSe Ocean that several screw ships have been seen shelling mutant communities and have engaged several ancient 'Mecha'. The owners of such powerful artifacts are unknown at this time
The legends of screw ships controlled by the ghosts of ancients haunts the harbors of Mutant Future.
From time to time new tales circulate through the bars, brothels, and harbor front hangouts of mutant sailors of these 'demon ships' taking sailors down to the atomic fueled hells of the Ancients.
Most are dismissed as pure backwash but occasionally a wreck will turn up with weird patterns upon the remains of its prow or body of a boat and the rumors begin anew. Many sailors curse the dark of the seas then and pray for a run that will not take them near the haunts of these supposed 'devil ships'.